We don't normally stay in one place for a more than a night or two anyway, so it's only been an issue once. We were at Galveston Island State Park waiting for some friends (from Galveston) to leave on a longer trip. They were ready a day earlier than expected. Since we left early in the morning, before the usual check out time, there was no problem getting a refund for the night that we didn't stay.
A good traveler has no fixed plans, and is not intent on arriving. ~ Lao Tzu